Float construction for hydroplanes



S 3 1930- A. ROHRBACH 1,776,336

FLOAT CONSTRUCTION FOR HYDROPLANBS' I Filed Feb. 27, 1929 2 sums-sun 1 INVENTOR 050 071 ROZ/"Zac ATTORNEYS Sept. 23, 1930. v ROI-{REACH 1,776,336

noA'r cous'rnucnoN FOR aynxoruns Filed Feb. 27, 1929 2 Shuts-Sheet 2 INVENTOR Y mmpa, QM W0 1 ATTORNEYS Patented Sept. 23, 1930 UNITED STATES PATENT OFFICE anoLr BOERBACH, or nnnnm-wnnnasnoar, GERMANY FLOAT CONSTRUCTION FOR HYDBOPLANES Application filed February 27, 1929, Serial No. 343,124, and in Germany February 27, 1828.

This invention relates to a boat or float structure, intended principally for use as hull construction for hydroplanes, and for floats that are used for supporting flying boats while resting upon or rising from the water.

The design embodying the invention provides an upper body or hull portion above the submersible bottom which upper hull has flaring or diverging side walls so that at its narrowest portion it is wider than the widest portion of the submersible lower body or bottom. This bottom body is intended to facilitate the gliding 'action upon the surface of the water of a hydroplane or other form of boat; and also for enabling a flying boat to take-0E from the water with greater ease and less resistance to its motion upon or through the water in the act of taking off. The invention maybe a used to advantage with a boat or float having its bottom surface arranged in step formation, or the invention may be used in connection with boats or floats not so constructed.

When used with a float having its bottom surface arranged in stepped formation, the.

invention is useful and of advantage providing increased space in the upper portion of the hull in combination with a submersible hull portion or bottom which is useful in reducing the tendency of the water-waves to cling to the sides and bottom of the hull, which clinging action produces friction and increases the resistance to movement of the.

room or cargo space without necessitating a proportional increase of width of the bot tom. As a result, the weight of the bottom has not been increasedsince by the present invention substantially the same bottom girdlo ers are employed as in the prior structure, the necessary strength being obtained wlthout waste 0 constructive material or increased weight.

A further advantage results 1n the use of the invention in transport planes, the gain of space toward the ceiling or top deck resulting in increased comfort to the .passengers. Moreover, the enlar ement of the upper hull structure or body cabin accommodates larger 00 quantities of luggage or freight and affords additional room for parts such as bilge p ping and control pulleys; while also enlarging the field of view of the persons carrled. In the case of war planes this divergence of a! the upper walls increases the flung range. Furthermore the overhanging S1d6 W8l-lS 1Iltercept lateral waves so as to prevent or m1n1-- mize the influx of spray? In the respects noted the present invention is an improvement on the invention d sclosed in my copending application, Ser al No. 184.751 filed April 18,1927.

My invention is illustrated in the accompanying drawings which form a part'of thls specification. In the drawmgs,

- Fig. 1 is'a front elevation of a flying boat the hull of which and also the supporting floats are constructed in accordance with this invention.

Fig. 2 is a side elevation of the same boat.

Fig. 3 is a side elevation partly 1n sectipn.

Fig. 4 is a transverse sectlon on the line 11-11 of Fig. 3. I a

Fig. 5 is a front elevation of the bow of a boat or float illustratingfthe development of the forward lidin sur aces.

Figs. 6 and 7 are respectively side'andbottom views of the construction shown 1n Flg. 5.

Referring to Figs. 1 and 2, the hull structure of the boat is indicated by reference numeral 16, and the floats by numeral 17. In these views the hull of both the boat and float structures is shown as having upwardly and outwardly flaring sides, the width of-the bottom of the hull in contact with the water being somewhat less than the greatest crosssection' width of the boat. As indicated, three motors 2 may be employed, arranged above the monoplane wings 1 and braced" against the latter by struts 3. Truss members 4 serve as connections for theinc'lined struts thus supplementing the latter. The high-deck wings I comprise longitudinal beams 9, 10, which are connected by spaced cross ties 8, a suitable covering or skin being Referring to the Figures 3-7 inclusive,

comprising Sheet 2 of the drawings, it will be found that I provide a sharp keel b which at the forward end of the ship or float may be continued to form a prow structure.

At the forward end a of the bottom at of the boat a, and extending forwardly of the first step m, I provide on each side of the keel b one or more concave surfaces 6 which may be designated as gliding surfaces. In Figs. 3 and 4 one such a concave surface or groove e is provided at each side of the keel, andthe effect upon the bottom surface of the hull with this construction is well illustrated in the sectional view of Fig. 4. The depth of the concavity preferably diminishes somewhat toward the forward end of the ship and the gliding surfaces are combined with the remainder of the forward bottom part of the ship or float in a proper manner to give to the bottom surface the proper desirable angle of incidence. 1

It is to be noted that the gliding surfaces e meet the upwardly and outwardly flaring sidewalls of the hull at a somewhat acute angle, shown at c the effect of which, as in taking off, is to direct the water downwardly and prevent, in an appreciable measure, the tendency of the water to rise and cling to the sides a of the hull. This same result and effect is augmented and increased by adding to the number of gliding surfaces or grooves to either side of the keel, and an eflective arrangement of this kind is illustrated in Figs. 5-7, in which the additional and symmetrically arranged surfaces are illustrated at t. By this construction additional edges t are provided, which, in a similar Way to that described in connection with the edge 0', counteract the clinging tendency of the water and waves to the sides of the hull.

The further advantage in this construction is that it aflords a hull which is wider in average beam and deck. than is the bottom. A substantially lighter hull structure is provided by my invention in which only light weight stiffening girders are required in the bottom a. The hull structure, above the water line with its outwardly flaring sides provides enlarged space within the hull for the more adequate and comfortable accommodation of passengers on seats 0 and cargoes. Nets p are provided above the seats 0. In the roof there are channels for control cables 8 leading from the pilots seat to the ailerons r and the tail planes (1; and also for bilge pipes u or the like. From the sight lines '0, shown in broken lines in Fig. 4, it appearsthat particularl in the downward direction there are wide elds of vision meeting below the bottom '01; in an extension of the bottom part disposed in front of the step m. The side floats 2' shown in Fig. 4 are constructed in accordance with the principles of the invention.

With ships or floats havin stepped bottoms, the modified bottom sur ace w1th gliding surfaces need not extend rearwardly of the first step, but I do not desire that this invention be understood as limited to a stepped hull construction, since it, will be clear that it can be used to advantage with other lmown types of hulls, and with all of the advantages herein set forth. Obvious changes to details of construction illustrated may be made and will be suggested toone scope of my invention.

What I claim and desire to protect by Letters Patent is:

1. A floating body for hydroplanes having a stepped bottom laterally curved forward of the step between the keel and chines to provide concaved sides whose vertices are higher than the chines, the side walls of the upper body portion above the chines flaring outward and upward so that said upper body portion at its narrowest is wider than the submersible part of the'floating body at its widest.

.skilled in the art withoutdeparting from the 2. A floating body for hydroplanes having 7 a stepped bottom laterally curved forward of the step between the keel and chines to provide concaved sides whose vertices are higher than the chines, the bottom being provided at a substantial distance aft of the bow with relatively short and narrow gliding surfaces adjacent to the keel and terminating at the step, the side walls of the upper body portion above the chinesflaring outward and upward so that said upper body portion at its narrowest is wider than the submersible part of the floating body at its widest.

3. A hydroplane comprising a main body structure and two separate float structures spaced laterally from the body structure, the body structure having a stepped bottom lat,- erally curved forward of the step between the keel and the chines to provide concave sides,

the side walls of the upper portion of the body structure above the chines flaring outward and upward so that the upper body por tion of the body structure at its narrowest is wider than the submersible part at its widest, the two lateral float structures each having a bottom of pronounced V-shape with the walls above the bottom diverging upward and outward.

In testimony whereof, I have signed my name to this specification.

ADOLF ROHRBACH. 

